A premier Sierra ski resort that seven years ago was raided by armed federal agents investigating environmental abuses earned top honors in an environmental scorecard released Monday by conservationists.

Squaw Valley USA’s A grade in the Ski Area Citizens Coalition’s annual ranking is part of a trend of improvement, members of the group said.

But officials at Kirkwood Mountain Resort, which received a failing grade for the second straight year, insist important efforts on behalf of the environment are being overlooked in a process that punishes any resort that attempts to improve and remain competitive.

The coalition ranks resorts on a numerical basis. Points can be lost for resorts that expand ski runs, or build new lifts, snow-making systems or condominiums. Points can be added for resorts that recycle, support renewable energy and expand mass transit.

Squaw’s score is largely due to efforts to reduce energy consumption through use of energy-efficient snow guns, using biodiesel in the resort’s fleet and retrofitting old buildings, the coalition said.

It’s also because there’s been no repeat of the type of problems that led to a 2000 raid by U.S. Environmental Protection Agency agents probing alleged violations from construction that polluted a tributary of the Truckee River.

Squaw Valley Ski Corp. in 2005 agreed to pay California $900,000 to settle a lawsuit filed in connection with the dispute.

Recent efforts to aid the environment at Squaw mirrors similar improvements made at the Sierra’s Mammoth Mountain, Colorado’s Telluride ski resort and Park City in Utah, the coalition said.

“These ‘comeback kid’ resorts are now biting at the heels of the ski industry’s environmental leaders,” said Autumn Bernstein of the Sierra Nevada Alliance, a member of the coalition.

“Squaw is a great example of a resort that has not only stopped the bad things they used to do, but is also taking on some more proactive programs,” Bernstein said.

Squaw representatives said they are proud of their grade and acknowledge problems in the past make the turnaround particularly important. Squaw had consistently earned a D grade but is on an improving trend, with this year’s grade following a B last year.

“Going from where we were to where we are now is a great thing,” Squaw spokeswoman Savannah Cowley said. “People are noticing what we’re doing, that we’re improving. It’s hard once you have a black mark in your past to change people’s perceptions.”

What has occurred at Squaw and several other resorts represents an important change in direction, said Ryan Demmy Bidwell, executive director of the coalition’s Colorado Wild.

“Cleaning up your act, and improving your score, is very possible,” Bidwell said. “But it does require more than lip service and marketing rhetoric.”

But some resort operators remain critical of the process, including Kirkwood, which got an F this year and last.

“Kirkwood has done an exceptional job at taking steps toward addressing environmental concerns,” said David Likins, the resort’s chief executive officer. “The question is, ‘is the resort taking steps to preserve the environment?’ and the answer for Kirkwood is a resounding ‘yes.’”

Kirkwood recently undertook efforts to cut energy consumption by reducing lighting, to promote carpooling by workers and guests, reduce the amount of waste sent to landfills and to save water, Linkins said.

Yet those steps receive little attention in the scorecard ranking, largely because the resort is now in the process of expanding lifts and snowmaking and building condominiums, Likins said.

“There is a very strong bias against growth,” Likins said.

The same concern was issued by operators of Mount Rose Ski Tahoe, even though this year the resort’s ranking rose from C to a B. Bernstein said the upgrade resulted from the installation of more energy efficient snow guns at Mount Rose.

“You cannot get a good grade if you’re trying to grow,” said resort spokesman Mike Pierce. “If you stay stagnant, they like you.”

Ski resort environmental scores

Boreal Mountain Resort: B, 68.9 percent

Alpine Meadows: A, 73.8 percent

Homewood Mountain Resort: B, 65.3 percent

Kirkwood Mountain Resort: F, 37.8 percent

Northstar-at-tahoe resort: D, 48.5 percent

Sierra-at-Tahoe resort: B, 65.8 percent

Squaw Valley USA: A, 70.7 percent

Sugar Bowl: C, 60.5 percent

Heavenly Mountain resort: C, 50.25 percent

Mt. Rose Ski Tahoe: B, 65.4 percent

Source: Ski Area Citizens Coalition